JPS62211914A - Device for vapor growth of semiconductor thin film - Google Patents

Abstract

PURPOSE:To restrain a curl-up of a gas by making a flow of the gas in a reactor tube uniform by providing a shielding cylinder with through-holes of twice number as that of exhaust vents so as to divide the gas for exhaust. CONSTITUTION:A shielding cylinder 15 is provided with through-holes of twice number as that of exhaust vents 6 and which have roughly the same diameter as an inner diameter of the exhaust vents 6. A gas is divided to be exhausted from the through-holes 15a of the shielding cylinder 15 and this is equivalent to that the exhaust vents becomes twice and accordingly, a flow of the gas becomes uniform. As a result, a curl-up of the gas in the part where a gas velocity is slow is restrained.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a semiconductor thin film vapor phase growth apparatus.

(Prior Art) A conventional reactor for vapor phase epitaxy of semiconductor thin films is shown in Fig. 8(A).
Shown in (B) and (C). In FIG. 8(A), a substrate 1 is placed in a carbon susceptor 2-1- and is heated by high-frequency induction from the outside by an RF coil 3 and maintained at a predetermined temperature. The raw material gas 5 introduced together with the carrier gas through the gas inlet 23 of the reaction tube 4-L section causes a reaction such as thermal decomposition near the substrate, thereby depositing a thin film on the substrate 1''2. After the reaction is completed, the gas is captured through the exhaust port 6. To improve the uniformity of the thin film, the carbon susceptor 2 is rotated by a rotating shaft 7 during growth. 8 is cooling water.

Further, FIG. 8(B) shows a vapor phase growth apparatus for compound semiconductor thin films such as GaAs and GaAJIAs.

In thin film vapor phase growth equipment for GaAs, GaAs, etc., if the reaction tube is exposed to air! To prevent this from deteriorating the properties of the membrane, a front chamber 9 for substrate exchange is provided at the bottom of the reaction tube as shown in the figure. The figure shows the state during growth. When replacing the board, lower the rotating shaft 7 and remove the gate valve 10.
is closed, the reaction tube 4 and the front chamber 9 are shut off, and the substrate exchange is performed through the window for substrate exchange. During growth, it is the same as in FIG. 8(A), but a fist plate 11 is provided in the middle of the rotating shaft 7, so that the gas after the reaction is completed flows into the front chamber 9, and the reaction products adhere to the front chamber. The structure is designed to prevent

Note that 12 is a window flange for board replacement.

Next, FIG. 8(C) shows an apparatus for mass production, in which a truncated pyramid-shaped carbon susceptor 13 having a cap 13a is used, and a substrate l can be installed on each side of the carbon susceptor 13. There is.

It is functionally similar to FIG. 8(B). In this case, since the diameter of the reaction tube becomes large, it is preferable to provide a plurality of exhaust ports 6 as shown in the figure to ensure a uniform gas flow. In the figure, there are two exhaust ports. Figure 8 (D)
is a cross-sectional view of the reaction tube of FIG. 8(C). Figure 8 (A
), (B) or (C), the same symbols indicate the same thing.

In FIGS. 8(A) to 8(D), (a) and (b) show gas flows within the reaction tube.

(Problem to be solved by the invention) However, in the apparatuses shown in FIGS. 8(A) and (B), the gas velocity on the exhaust port side (A) of the reaction tube 4 and the opposite side (B) is large on the side (A). It becomes smaller on the side (A). For this reason, gas swirling is observed on the (a) side, and reaction products adhere to the upstream portion of the susceptor 2 on the inner wall of the reaction tube. On the other hand, in Fig. 8(C), the exhaust port 6
The same thing can be said for the middle (A) portion of the exhaust port 6 (see FIG. 8(D)). Since the products adhering to the reaction tube are extremely unstable, they fall onto the substrate 1 during growth, causing surface defects in the thin film. Although this can be prevented by increasing the gas flow rate, the yield of raw materials decreases, which impairs economic efficiency. It is also possible to increase the number of exhaust ports, but this method is difficult due to structural constraints.

(Means for Solving the Problems) The present invention has been made in view of the drawbacks of such semiconductor thin film vapor phase growth apparatuses, and is intended to eliminate these drawbacks of conventional semiconductor thin film vapor phase growth apparatuses. .

That is, the present invention provides a thin film vapor phase growth apparatus, by providing a cylindrical jacket part inside a cylindrical part provided with an exhaust port, and opening twice the number of through holes in the jacket part as the number of exhaust ports. The present invention provides a semiconductor thin film vapor phase growth apparatus characterized by uniform exhaustion.

(Example) Next, the present invention will be explained according to illustrated embodiments.

FIG. 1 is a sectional view of a main part of an embodiment of the present invention corresponding to a conventional semiconductor thin film vapor phase growth apparatus that does not have a front chamber (see FIG. 8(A)). The structure is such that a blocking cylindrical part 15 is provided inside the cylindrical part 14 to create a closed space 21. The shielding cylindrical portion 15 has twice the number of through holes as the number of exhaust ports, each having a diameter equivalent to the inner diameter of the exhaust ports. FIG. 2(A) is a sectional view taken along the line AA' in FIG. 1, and FIGS. 2(B) and 2(C) are other embodiments. As is clear from the figure, the position of the through hole 15a of the cylindrical portion 15 is such that it is located between the exhaust ports 6 (if there are two or more exhaust ports), or the exhaust port 15a is located between the through holes 15a.
(if there is one exhaust port). Second
In the figure, (A), (B), and (C) are exhaust ports 1 and 2, respectively.
．． This is the case of three pieces. The flow of gas is shown by arrows in Figure 2, but since it is divided and exhausted through the through holes 15a of the cylindrical part 15, it is equivalent to doubling the number of exhaust ports, and the reaction takes place. The flow of gas in the tube becomes uniform. As a result, gas swirling up in areas where the gas velocity is low is suppressed.

In fact, when the following parameters are used in a structure in which the inner diameter of the blocking cylinder matches the diameter of the reaction tube as shown in Figure 1, it is possible to prevent reaction products from adhering to the inner wall of the reaction tube on the upstream side of the susceptor. The surface defects of the thin film were reduced.

The relationship between the diameter of the reaction tube, the number of exhaust ports, and the diameter of the through hole in the cylindrical part for the barrier in the apparatus shown in FIG. 1 will be illustrated below.

Reaction tube diameter (glazed layer), number of exhaust ports (pieces), and hole diameter (diaphragm)
FIG. 3 is a sectional view of a main part of another example of the present invention, in which a funnel-shaped shield 16 is used in place of the cylindrical portion 15 for cow shielding shown in FIG. 1, and the inner diameter of the base 16a is smaller than that of the reaction tube. This is an example. A through hole is provided in the base 16a. According to this embodiment, the uniformity of the gas flow is further improved by discharging the gas from around the shaft in a funnel shape.

Components other than the scenery are the same as those in the embodiment shown in FIG. 2, and the same reference numerals as in FIG. 2 mean the same things.

FIG. 4 is a sectional view of a main part showing an embodiment of a semiconductor thin film vapor phase growth apparatus having a front chamber 9 as shown in FIGS. .

In addition, FIG. 5 shows a closed space 21 using a shielding cylindrical part 18 and a shielding plate 11 for preventing reaction products from adhering to the front chamber.
is making. The shield plate 11 is fixed to the rotating shaft 7.

FIG. 4.5 The arrangement of the through holes in the cylindrical part 17, 18 for the shield and the like are the same as in FIG. 2.

FIG. 6 is a sectional view of a main part showing another example of the semiconductor thin film vapor phase growth apparatus of the present invention, in which a similar shielding cylindrical part 20 is further provided inside the shielding cylindrical part 19. . FIG. 7 shows a sectional view taken along line A-A' of the device shown in FIG. 6. In this case, the number of through holes 20a in the shielding cylinder 20 is twice the number of through holes 19a in the shielding cylinder 19 as before. 21.22 in the figure indicates a closed space.

In FIGS. 6 and 7, the points other than those mentioned above are the same as those described with respect to FIGS. 1 to 5 above.

(Effect of the invention) By making twice as many holes as the exhaust ports in the shielding cylindrical part and discharging the reactor separately, the flow of gas in the reaction tube becomes uniform, and gas swirling can be suppressed. can. As a result, adhesion of reaction products to the susceptor's first flow side is eliminated, and surface defects in the thin film are eliminated. Therefore, according to the apparatus of the present invention, a high quality semiconductor thin film can be grown without reducing the raw material yield.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of essential parts of an embodiment of the semiconductor thin film vapor phase growth apparatus of the present invention, FIG. 2 (A) is a cross-sectional view taken along the line AA' in FIG. ) is a sectional view of another example. 3 to 6 are sectional views of main parts of other examples of the device of the present invention,
FIG. 7 is a sectional view taken along the line AA' in FIG. 6. Figures 8(A), (B), and (C) are cross-sectional views of a conventional semiconductor thin film vapor phase growth apparatus, and Figure 8(CD) is a cross-sectional view of a conventional semiconductor thin film vapor phase growth apparatus.
1 shows a cross-sectional view of a reaction tube. Explanation of symbols 1... Substrate 2... Susceptor 4... Reaction tube 5... Raw material gas 6... Exhaust port a... Rotating shaft 9... Front chamber 11... Shield plate 13 ...Susceptor 14...Cylindrical part 15 for mounting the exhaust port...Cylindrical part 15a...Through hole No. 1 Fig. 3 Fig. 2 Fig. 2 (A) (B) (C) Figure 4 Figure 5

Claims (1)

[Claims] The thin film vapor phase growth apparatus is characterized in that a cylindrical shield part is provided inside a cylindrical part provided with an exhaust port, and the shield part is provided with through holes twice the number of exhaust ports to uniformly exhaust the air. Semiconductor thin film vapor phase growth equipment.